. Fresh-water biology. Freshwater biology. FREE-LIVING NEMATODES ,487 19 (18) Main tooth submedian. Lips thin; setae present 20 20 (21) Males without bursa Oncholaimus Dujardin. / : III Genus of numerous species, nearly all marine. A few species only in brackish and fresh water. Cosmopolitan, extend- ing well into the polar seas. Some attain a length of 25 to 30 mm. The individuals sometimes occur in enormous numbers. The pharyngeal teeth vary in number, form, and size, and afford good specific characters. The segments of the esopha- gus frequently contain much-branched "salivary" gl
. Fresh-water biology. Freshwater biology. FREE-LIVING NEMATODES ,487 19 (18) Main tooth submedian. Lips thin; setae present 20 20 (21) Males without bursa Oncholaimus Dujardin. / : III Genus of numerous species, nearly all marine. A few species only in brackish and fresh water. Cosmopolitan, extend- ing well into the polar seas. Some attain a length of 25 to 30 mm. The individuals sometimes occur in enormous numbers. The pharyngeal teeth vary in number, form, and size, and afford good specific characters. The segments of the esopha- gus frequently contain much-branched "salivary" glands emptying through the pharyngeal teeth. The female sometimes possesses a pecu- liar pair of relatively large organs of un- known significance emptying through pores toward the tail end. Representative species. Oncholaimuspunctatus Cobb 1914. 7 1? 10. ;i -M-« 92 . i—" 12/ 2 2 2 8 ' " ™»'. X887 Fig. 783. Oncholaimus punctatus. a, thin flaps on margins of lips; h, lips; c, anterior circlet of papillae; d, poste- rior circlet of papilla-like cephalic setae; , subme- dian tooth or onch us; of pharynx; h, intestine; i, ejaculatory duct; j, spic- idum; k, dorsal tooth or onchus; /, amphid; m, am- pulla of gland, emptying through dorsal onchus, k; «, rectum; 0, beginning of esophagus; ^, anus; g, lin- ing of esophagus; r, caudal gland; 5, caudal papilla; ty ducts of the three caudal glands;«, spinneret. (After yit ^^^ . .„ Cobb.) "4=£==^ X4S7 21 (20) Males with bursa. Oncholaimellus de Man. Much like Oncholaimus, but males have narrow bursa. Spicula unequal, or equal. Two species known; the type 0. calvadosicus de Man is marine. Representative species. Oncholaimellus heterurus Cobb 1914. It is rather difficult to observe the finer details of the cuticula on account of the presence in it of numerous dot-like ele- ments, which are arranged in longitudinal groups, of which the widest are the lateral groups. The longitudinal arrangement of
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
